This invention relates to activated micropipette tips used for diagnostic test devices, and more particularly to an improved such tip which contains a reactive element which readily captures molecules from fluid samples drawn, through the tips, thus permitting such samples to be assayed more efficiently and rapidly than was heretofore possible. This invention relates also to novel methods of preparing the reactive element and assaying such fluid samples.
Existing assay formats of the type described are generally rather cumbersome and time consuming procedures, and frequently require the handling or transfer of the fluid samples and test reagents between multiple receptacles, such as for example between plastic test tubes, transfer pipettes, reaction vessels, etc. Multiple transfers of samples and/or reagents frequently result in a loss or contamination of the sample, thereby reducing the overall efficiency and sensitivity of the assay.
For example, conventional assay formats rely upon passive diffusion to bring together receptor and ligand, such as an antibody and antigen. Typically this would include the non-covalent coating of the wall or surface of a glass or plastic tube or microtiter well with an antibody, thereafter incubating a sample antigen into the coated tube or well (receptacle) to allow the antigen and antibody to bind, thereafter employing a stringent wash to remove non-specific binding, and then effecting quantitation of the bound ligand, for example by binding to a second labeled antibody.
Efforts have been made to utilize a spherical receptor bead for blood analyzing apparatus (see U.S. Pat. No. 4,749,658), but in that case the receptor was simply placed in the bore of an aspirating type cartridge, and was allowed to float freely between the operating piston of the device and the sample ingress/egress end of the cartridge. The receptor was not mounted in a disposable pipette tip designed to generate turbulence in the vicinity of the receptor upon the ingress or egress of a sample.
The related U.S. Pat. Nos. 4,753,775, 4,775,635 and 4,806,313 also disclose the use of receptors in a pipette having a bulbous upper chamber which can be flexed to cause fluid samples to be drawn or discharged past the receptors, but the receptors are not mounted in a disposable tip designed to create turbulence adjacent a receptor.
It is an object of the present invention, therefore, to provide an improved pipette tip and associated assay element which will eliminate many of the problems heretofore associated with the handling of samples during assay protocols.
To this end it is an object of this invention also to provide an improved sample transfer device in the form of a pipette tip containing a reactive element having a controlled, predetermined surface area.
Another object of this invention is to provide an improved transfer device of the type described capable of handling larger or increased sample volumes as compared to conventional microtiters or tubes.
A further object of this invention is to provide an improved transfer device containing a reaction element to which the linkage can be of the covalent or non-covalent variety.
A more specific object of this invention is to provide an improved tip of the type described which contains a novel, hydrodynamically designed receptor element for quickly capturing molecules from a fluid sample passing through such tip.
Still another object of this invention is to provide improved methods for preparing reactive elements and effecting assays of the type described.
Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.